Spark-plug.



l. MK IVICKERNN.

SPARK PLUG.

APPLICATION FILED luLY 20. |911.

Ratented Sept. 17, 1918.

son eterni/fav ses STATE@ y JOSEPH M. Henneman, or sr. LOUIS, M1SSoUnI'Ass1en`on or ONE-Entrare Devin M.

HU'ICHINSON, OF ST. LOUIS, MISSOURI. A

Specification of Letters Patent.

Patente sepa ri, rais,

Application-filed July/.20, 1917. Serial No. 181,637.

To all whom t may concern: I

Be it known that I, JOSEPH' M. McKenvNAN, a citizen of the Unitedl States, residing able others skilled in the art to which itap-A pertains to make and use the same. This invention relates to spark plugs. The eXtreme usefulness of electrical intensifiersor spark gap mechanism has longv been acllznowledged` and earlier experimenters considered it necessary to make the spark plug and spark gap intensifiers as separate and distinct devices but later inventors have combined the two devices into the spark plug tion, lcbviat' g and overcoming' the diiiculties encoui tered in other devices of the same character, which diiliculties'will be hereinafter mentioned as the description proceeds. With this object in vieW the invention consists in the improved construction, arrangement and combination of parts hereinafter fully described and afterward specifically claimed.

In order that the construction and operation thereof may be readily comprehended,

' I have illustrated an approved embodiment ofl the invention in the accoinpanyin drawings and will now roceed to fully escribe the same, having re erence to said drawings,

' in, Which- Figure 1 represents the invention in sidev indicates the body of the plug threaded at 4' to engage a threaded opening in the cylinder of the motor, the body forming the lectrode. Atl 5 the interior of the 'body is enlarged, forming a shoulder 6 upon which rests a' shoulder on the insulating 4 inner 4sleeve 7, the upper portion of the enlarged op'enlng of the body'being interiorly threaded, as at 8 to receive the exteriorly threaded end vof a sleeve 9, which engages a shoulder 10 on the inner insulating sleeve 7 .Lf

Frictionally engaged -in the up er end of the sleeve 9 is'the insulating hea llvwhich is held from entering too far bya' shoulder 12 which engages the upper end-'of sleeve 9, the shoulder extending laterally. `seine distance and being undercut, as at 12B, so that rain, or other water will drip oi` and not gather. between' the shoulder 12 andthe steel sleeve 9 andthus form a conductor to short-circuit'between the terminal and said sleeve.

The insulating members 7 and 11 are made oi' any suitable insulating material such as porcelain, stone, iiber or the like, and are both provided with central longitudinal bores in alinement with each other as at 13 and 14, 'in the first of which is rigidly mounted an electrode 15 the lower end of the bore 13 being enlarged at 16, and the lower end of the electrode 15 being reduced as at 17 and extended through andbeyond bod 3 in position to coperate with the spar point 18 secured in the usual manner to the body 3, the spark point being curved in-4 v ward, as usual, toward the lower end of the electrode 13 and iattened vertically at its end in order to give a flat and widened spark. A

A threaded electrode 19 mounted in the bore 14, is vthreaded through two bearing nuts, one, as at 20, beinv fixed in a recess in the bottom, and the ot er, as at 21, fixed in a recss in the top of thev insulating member 11, a jam nut 22 being` placed above the nearing nut 21 to vlock the electrode 19 in adjusted position to properly spacev the points of the electrodes 13 and 19 at .tlife spark gap 23, the sleeve 9 being providef-gy with point.

Upon the upper end of rod 19.is threaded a hand nut 24 by means of which the our .rent conducting wire, attachedfto the rod 19, may be securely yheldv by clamping it against the jam nut 22, the latter vbeing .the usual opposite sight openings;`A through which to observe the action at thls recessed in its underside, as at 25, to-accommodate a spring washer 26,'which pra former by contact with and-pressure upon 'the former.

vents injury to the insulator 11,. or the nuts coming loose, or changeA in the spark gap. A suitable packing washer-` 27 is pla between the shoulders of the insulator 7 and the metallic body 3 to prevent injuryto the The operation of the, invention. willl be readily comprehended by those skilled in the art and no extended description 'thereof By the construction described l have remedied many defects which 'I have encountered in using spark plugs.

By reducing the diameter -ofthe interior of the body at the bottom I have left a shoulder to supportv the' lower or skirt part of the-insulator sleeve so that if the latter should break, at the shoulder, they frev,

` often occurs and causes the member to jam,

rendering it impossible to screw it far.

enough to properly regulate the spark gap. Very often, also, this member becomesv Worn because of the nature of the 'material of which it is made and will not hold so that it works upward and so 'widens the spark gap that the current will not jump laying handled thousands of plugs, my

aardse? ractical experience teaches me that my plug' 1s more economical to manufacture, more simple, and stronger and more durable and dlelaendable,c than any other with which I vam a uainted and assembles easily with, any or mary wrench. Allspecial tools are rendered unnecessary and threaded fiber parts are avoided.

The upper part of my plug will apply to many now in use and may be marketed.

separately for such purpose.

Having thus fully described my invention', what I claim as newand desire to secure by Letters Patent of United States, is:

A spark plug comprising a body, an insulating member loosely fitting therein, au electrode bar carried by said insulating member, a metallic sleeve threaded into the upper, end of the body, an insulating member rictionally seated in the upper end of the sleeve and having a peripheral undercut shoulder bearing on the top thereof, and a central vertical bore with widened recesses at the upper and lower ends thereof, a bearing nut iXed in each of sa-id'reeesses, a threaded electrode bar loosely seated in the bore and projecting through said bearing nuts, a recessed jam nut on the bar above the upper bearing nut, and a spring washer arranged in the recessk of said jam nut to bear on the upper bearing nut to hold the adjacent relative parts in adjusted position. In testimony whereof I'liave signed my name to this specification in the presence oftwo subscribing/Witnesses.

JosnrH M. MCKERNAN.

Witnesses: v ALBERT E. SCHNEIDER, HERBERT C. REINERT. 

